Production of biodiesel

ABSTRACT

A process for the production of biodiesel is disclosed. In a preferred embodiment, the process is based on the production of biodiesel using refinery soapstock where the process is performed in an alcoholic medium resulting in the insolubility of certain byproducts. Other valuable products can also be obtained from the process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(e) to U.S.Provisional Application No. 60/655,458, filed Feb. 23, 2005, andBrazilian Patent Application No. 2004000005705, filed Dec. 20, 2004,which are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a process for the production ofbiodiesel using soapstock.

2. Description of the Related Art

Biodiesel is a clean burning alternative fuel, produced from domestic,renewable resources. Biodiesel is simple to use, biodegradable, andnontoxic. Biodiesel is comprised of mono-alkyl esters of long chainfatty acids. These mono-alkyl esters of long chain fatty acids have beenderived from vegetable oils or animal fats.

The processes used today to produce the methyl or ethyl esters of fattyacids start from animal or vegetable oils (triglycerides), an esteemedmaterial that has better application in human and/or animal food.Accordingly, because of the importance of animal and vegetable oils asfood, the use of animal and vegetable oils in the energy matrix as rawmaterial for the manufacture of biodiesel results in an overall waste.

Processes are available to use the fatty acids from soapstock, aresidual by-product from the production of the edible oils and fats, toproduce biodiesel. However, these processes produce a great quantity ofresidual acid-water due to the acidulation of the soapstock withsulfuric acid. The residual water is acidic, has high sodium sulfatecontent, and has a very high Biochemical Oxygen Demand (BOD) because ofthe lecithin, gums, and other organic impurities present in the effluentwater. The high cost of the treatment of the effluent water coming fromthe acidulation of the soapstock makes the process economicallyunviable. The treatment of this residual effluent is an extremelycomplicated problem from an environmental point of view. The problem istechnically difficult to solve because of the water's high content ofsodium sulfate and the high BOD resulting from the gums, lecithin, andother organic impurities.

SUMMARY OF THE INVENTION

Accordingly, there exists a need to turn the production of biodieselfrom refinery soapstock into a feasible process from an economic andenvironmentally adequate point of view.

One embodiment provides a process for producing biodiesel comprising:saponifying a soapstock with an alkaline base in an alcohol to yield asaponified soapstock; filtering the solution of saponified soapstock toremove substantially insoluble organic material; adding a mineral acidto the filtered solution of saponified soapstock to form fatty acids anda mineral salt; and esterifying the fatty acids, thereby formingbiodiesel.

Another embodiment provides biodiesel obtained from a processcomprising: saponifying a soapstock with an alkaline base in an alcoholto yield a saponified soapstock; filtering the solution of saponifiedsoapstock to remove substantially insoluble organic material; adding amineral acid to the filtered solution of saponified soapstock to formfatty acids and a mineral salt; and esterifying the fatty acids.

Another embodiment provides sterols obtained from a process comprising:saponifying a soapstock with an alkaline base in an alcohol to yield asaponified soapstock; filtering the solution of saponified soapstock toremove substantially insoluble organic material; adding a mineral acidto the filtered solution of saponified soapstock to form fatty acids anda mineral salt; esterifying the fatty acids; removing insolubleimpurities after the esterification; and distilling the solution ofesters of fatty acids after esterification to obtain sterols.

Another embodiment provides organic material obtained from a processcomprising: saponifying a soapstock with an alkaline base in an alcoholto yield a saponified soapstock; and filtering the solution ofsaponified soapstock to obtain substantially insoluble organic material.

Another embodiment provides mineral salts obtain from a processcomprising: saponifying a soapstock with an alkaline base in an alcoholto yield a saponified soapstock; filtering the solution of saponifiedsoapstock to remove substantially insoluble organic material; adding amineral acid to the filtered solution of saponified soapstock to formfatty acids and a mineral salt; and separating the mineral salt from thesolution.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Preferred embodiments provide a process for the production of biodieselutilizing soapstock as a starting material. Soapstock, as a refining oilbyproduct, is an abundant, under-utilized, and inexpensive startingmaterial. Advantageously, the preferred process to obtain biodiesel doesnot substantially use vegetable or animal oils as raw material, whichcould find better applications in animal and human food. Also, thepreferred process is environmentally friendly, as the process does notgenerate large quantities of residual acid water. The preferred processalso produces useful reagents, such as polypeptides, lecithin, sodiumsulfate, and sterols.

As used herein, biodiesel refers to mono-alkyl esters of long chainfatty acids, preferably methyl or ethyl esters. Preferred biodiesel madefrom various starting materials with various processes can confirm tospecifications. In the United States, the American Society of Testingand Materials (ASTM), a standard setting organization for fuels and fueladditives, defines biodiesel according to specifications.

As used herein, soapstock refers to a refining oil byproduct. Soapstockcomprises a cache of plant esters (sterols), glycerides (oils),phospholipids (lecithin), sodium soap.

A preferred embodiment uses soapstock, a residual by-product from theproduction of edible oils and fats. While there are other processesavailable which also use the fatty acids from soapstock, in contrast tothe preferred embodiments, these other processes produce a greatquantity of residual acid-water due to the acidulation of the soapstockwith sulfuric acid. Accordingly, there exists a need to turn theproduction of biodiesel from refinery soapstock into a feasible processfrom an economic and environmentally adequate point of view.

The processes are based on the production of biodiesel from thesoapstock of vegetable or animal oil refining. In one embodiment, theprocesses are preferably performed in an alcoholic medium, which resultsin the insolubility of byproducts. Consequently, certain problems of theprior art biodiesel productions, such as treatment of the residual waterwhich is acidic, has high sodium sulfate content, and has high BOD, arebypassed.

In one embodiment, a process for producing biodiesel is disclosed. Theprocess comprises: saponifying a soapstock with an alkaline base in analcohol to yield a saponified soapstock; filtering the solution ofsaponified soapstock to remove substantially insoluble organic material;adding a mineral acid to the filtered solution of saponified soapstockto form fatty acids and a mineral salt; and esterifying the fatty acids,thereby forming biodiesel. The process can further comprise neutralizingexcess mineral acid after addition of the mineral acid to the filteredsolution. The process can further comprise removing salts formed fromthe neutralization. The process can further comprise removing thealcohol after esterification. The process can further comprise removinginsoluble impurities after esterification. The process can furthercomprise distilling the esters of fatty acids after esterification.

In one embodiment, the process comprises the following steps:

-   -   (A) Treating a refinery soapstock with a strong alkaline base in        the presence of an alcohol. The saponification of the        triglycerides present in the refinery soapstock can be achieved        by treating the soapstock with a strong alkaline base. This        treatment can be conducted under heating and alcohol reflux.        Substantial triglycerides present are saponified by the strong        alkaline base.    -   (B) After finishing the reaction described in (A), the product        is filtered to remove substantially insoluble organic material.        This organic material comprises polypeptides and lecithin and        can be used as an emulsifying agent in industrial applications        or as an additive to animal feed.    -   (C) A strong mineral acid is then added to the alcoholic        solution. The mixture is then heated to around the boiling point        of the alcohol and refluxed. Fatty acids can form from the        respective soaps.    -   (D) In the reaction described above, a mineral salt can form        between the strong alkaline base component of the soap and the        strong mineral acid. The salt is not soluble or sparingly        soluble in an alcoholic medium, where the process is conducted.        Accordingly, filtration and removal of the salt from the        reactive medium is easy to perform. Generally, the filtered salt        is a technical grade and can be sold for industrial        applications.    -   (E) After filtering the salt, the material is heated under        reflux for esterification of the free fatty acids with the        alcohol already being used.    -   (F) After esterification, a certain quantity of base is added to        neutralize the excess mineral acid in the alcoholic solution.    -   (G) After neutralization, the solution is filtered again to        remove the salts formed during the neutralization.    -   (H) The clear solution of esters in alcohol is ready for the        removal of the excess of alcohol. This removal can be done by        distillation of the alcohol.    -   (J) After recovering the excess alcohol, insoluble impurities        are removed from the esters.    -   (K) The ester obtained after removal of insoluble impurities is        then distilled for purification resulting in biodiesel.

In another embodiment, the process comprises the following steps:

-   -   (A) Treating a refinery soapstock with a strong alkaline base in        the presence of an alcohol, such as ethanol or methanol. The        saponification of the triglycerides present in the refinery        soapstock is achieved by treating the soapstock with a strong        alkaline base, such as, but not limited to, sodium hydroxide or        potassium hydroxide. This treatment can be conducted under        heating and alcohol reflux. Substantial triglycerides present        are saponified by the strong alkaline base.    -   (B) After finishing the reaction described in (A), the product        is filtered to remove substantially insoluble organic material.        This organic material comprises polypeptides and lecithin and        can be used as an emulsifying agent in industrial applications        or as an additive to animal feed.    -   (C) A strong mineral acid, such as, but not limited to,        sulfuric, phosphoric, or chloridic acid is then added to the        alcoholic solution. The mixture is then heated to around the        boiling point of the alcohol and refluxed. Fatty acids can form        from the respective soaps.    -   (D) In the reaction described above, a mineral salt is formed        between the strong alkaline base component of the soap and the        strong mineral acid added. The salt is not soluble or sparingly        soluble in an alcoholic medium, where the process is conducted.        Accordingly, filtration and removal of the salt from the        reactive medium is easy to perform. Generally, the filtered salt        is a technical grade and can be sold for industrial        applications. In an embodiment, technical grade sodium sulfate        is obtained.    -   (E) After filtering the salt, the material is heated under        reflux for esterification of the free fatty acids with the        alcohol already being used.    -   (F) After esterification, a certain quantity of base, such as        calcium oxide, calcium hydroxide, or sodium carbonate, is added        to neutralize the excess mineral acid in the alcoholic solution.    -   (G) After neutralization, the solution is filtered again to        remove the calcium or sodium salts formed during the        neutralization.    -   (H) The clear solution of methylic or ethylic esters in alcohol        is ready for the removal of the excess of alcohol. This removal        can be done by distillation of the methanol or ethanol at        temperatures varying from 40° C. to 90° C., at ambient or at        reduced pressure (vacuum).    -   (J) After recovering the excess alcohol, the methylic or ethylic        esters are centrifuged to eliminate the insoluble impurities.    -   (K) The methylic or ethylic ester obtained in the centrifugation        process is then distilled under vacuum for purification        resulting in biodiesel.

Embodiments utilize soapstock as a starting material. Soapstock refersto a residual by-product from the production of edible oils and fats. Inone embodiment, the refining soapstock can come from soy oil refining orany other vegetable or animal oil chemical refining processes, such as,but not limited to, rice oil, sunflower oil, coconut oil, castor oil,chicken oil, cottonseed oil, corn oil, peanut oil, palm oil, and babassuoil. Preferably, soapstock is derived from oil selected from the groupconsisting of soy oil, palm oil, sunflower oil, and rice oil.

Soapstock water content will vary from process to process. A soapstockfrequently comprises about 40-80% moisture content; including, about60-70% moisture content.

In one embodiment, the process is performed in an alcoholic medium. Anyalcohol can be used such that the resulting biodiesel comply withspecifications for the biodiesel. Preferred alcohols include methanoland ethanol. Other alcohols include propanol, butanol, hexanol, andheptanol.

The preferred process is performed in an alcoholic medium and produceshardly any residual water besides that already contained in thevegetable oil refinery soapstock. Any residual water is substantiallyfree of inorganic salts and has almost no organic contamination.Therefore, treatment of the water becomes quite simple, and the usualwater treatment systems can make its reuse efficient and applicable.Thus, the energy balance resulting from this process is positive, forthe energy cost to produce biodiesel resulting from the preferredprocess is less than the energy generated by it. Accordingly, thepresent process turns the production of biodiesel from refinerysoapstock into a feasible process from an economic and environmentallyadequate point of view.

The saponification of soapstock in an alcoholic medium is facilitatedwith a strong alkaline base. A base that is soluble in the alcoholicmedium is preferred. Preferred bases include, but are not limited to,sodium hydroxide and potassium hydroxide.

When the processes are performed in an alcoholic medium, certainresulting byproducts are insoluble. Such byproducts can be filtered fromthe alcoholic medium. After the saponification of soapstock with thebase, there may be substantially insoluble organic material. Thisorganic material can comprise polypeptides and lecithin and can be usedas an emulsifying agent in industrial applications or as an additive toanimal feed.

The saponified soapstock comprises fatty acid salts (soaps). Addition ofa strong mineral acid to the fatty acid salts can yield respective fattyacids. A preferred acid facilitates exchange of ions to yield the fattyacids. Preferred acids include, but are not limited to, sulfuric acid,phosphoric acid, and chloridic acid.

The exchange of ions between the fatty acid salts and strong mineralacid also yields a salt. The salt may not be soluble or may be sparinglysoluble in the alcohol medium such that the salt can be removed from thealcohol medium easily. The recovered salt can be of technical grade. Incertain cases, the recovered salt can be reused in industrialapplications. In a certain embodiment, such as using a sodium cationcontaining base (e.g. NaOH) and sulfate anion containing acid (e.g.H₂SO₄) in the process, the salt is sodium sulfate.

After removal of the salt, the alcoholic medium containing the fattyacid is subjected to esterification conditions. The esterification isperformed with the alcohol already present. Alternatively, the alcoholcan be exchanged for another alcohol. Preferably, the esterification isperformed under acidic conditions. In an embodiment, the acidicconditions result from excess mineral acid that reacted with thesaponified soapstock. As stated above, preferred acids include, but arenot limited to, sulfuric acid, phosphoric acid, and chloridic acid.

After esterification, the excess acid is neutralized with a base. Anybase that can neutralize the excess acid can be used. The salt resultingfrom the neutralization may not be soluble or may be sparingly solublein the alcohol medium such that the salt can be removed from the alcoholmedium easily. Preferred bases include, but are not limited to, calciumoxide, calcium hydroxide, sodium carbonate, and sodium bicarbonate.

After neutralization and removal of salts, the alcoholic medium containsesters of fatty acid. Removal of the alcohol yields esters of fattyacids. Removal of the alcohol can be achieved through evaporation, suchas distillation. Preferably, the distillation can be performed attemperatures sufficient to remove the alcohol. The distillation can beperformed at ambient or reduced pressure. The boiling point of methanolis 64.5° C. The boiling point of ethanol is 78° C. Accordingly, ifmethanol or ethanol is used as the alcoholic medium, the distillationcan be performed at temperatures ranging about 40° C. to about 90° C. atambient pressure to remove the alcohol.

The distillation yields esters of fatty acids. Subsequent purificationof the esters of fatty acids can include eliminate insoluble impurities.The insoluble impurities can be removed by a separation means, such ascentrifugation or filtration. Preferably, the insoluble impurities areremoved by centrifugation.

Subsequent purification of the esters of fatty acids also can include adistillation. Preferably, the distillation after removal of insolubleimpurities is done under vacuum. The distillation after removal ofinsoluble impurities can yield valuable products, such as biodiesel andfurther products obtained from subsequent workup of the distillationresidue. Preferably, the biodiesel complies with specifications.

Purification of Distillation Residue

The distillation residue after obtaining biodiesel can be furtherworked-up to yield valuable products. One such product is sterols. Theremaining distillation residue after obtaining biodiesel is generallyneutral and has an average of about 2 to about 20% sterol content. Inanother embodiment, the sterol content is about 5 to about 15%. Inanother embodiment, the sterol content is about 10%. Examples of somesuch sterols and methods for obtaining purified sterols are described inU.S. Pat. No. 6,846,941, which is incorporated herein by reference.Sterols can be used as a supplement in the diet of animals and humans asa means to lower cholesterol in the blood serum. There is alsocommercial interest in the use of sterols as emulsion stabilizers and/orviscosity modifiers, especially in cosmetic formulas. Soybean oilproducers and soy-based sterol producers have interest in methods ofobtaining sterols.

The distillation residue after obtaining biodiesel can be submitted toadditional distillation conditions, such as those disclosed in U.S. Pat.No. 6,846,941, to obtain purified sterols. The sterols can be distilleddirectly in the thin film evaporation (TFE) under vacuum of about 30 toabout 1 mbar and temperature of about 150° C. to about 210° C. orfalling film evaporation (FFE) preferably under vacuum of about 1×10⁻¹mbar and temperature of about 180° C. to about 220 or 230° C. to removelighter volatiles. Then, on a subsequent distillation step, the residuecan be distilled in a short-path distillation preferably under vacuum ofabout 1×10⁻¹ mbar or lower and at a temperature of about 220 or 230° C.to about 240 or 280° C. A concentrated sterol fraction containing about40 to about 70% sterols can be obtained in some embodiments. Thedistilled sterols can be submitted to crystallization to produce purersterols.

In some embodiments, the process can further comprise distilling orevaporating one or more compounds selected from the group consisting oflights, medium-lights, and water from the distillation residue prior tothe distilling to separate at least a portion of the unsaponifiablecompounds.

The process of purification of the distillation residue begins byproviding the distillation residue after obtaining biodiesel, whereinthe distillation residue can comprise one or more unsaponifiablecompounds. The process further can continue by subjecting a mixture ofone or more unsaponifiable compounds to a distillation to form adistillate comprising at least a portion of more pure unsaponifiablecompounds.

In preferred embodiments, the process can further comprise subjectingthe distillate comprising at least a portion of the unsaponifiablecompounds to a subsequent distillation to form a second distillate and asecond residue, thereby further purifying and/or separating theunsaponifiable compounds.

The methods disclosed herein comprise multiple steps. Which steps areused will vary depending on several factors, including, but not limitedto, the identities of the starting material and desired target(s) andvaluable product(s). For some materials, it is desired to perform one ormore steps of pre-treatment with regard to cleaning up the material forfurther processing. Such cleaning methods include, but are not limitedto, rinsing, washing, filtering, and decanting.

In an embodiment, the process is performed in an alcoholic medium, whichgenerates sub-products from the contaminants with adequate quality to bemarketed directly, representing an additional source of earnings for theproduction of biodiesel. Because the process is preferably performed inan alcoholic medium, insolubility of certain byproducts results. Theseinsoluble byproducts can be easily separated. Separation is preferablyby filtration. The sodium sulfate produced is easily separated from therest of the process, and finds application in the industry generally ascommercial grade sodium sulfate. The organic byproduct materialcontaining materials, such as polypeptides and lecithin, is easilyseparated from the rest of the products and can be marketed as anindustrial emulsifier or animal feed additive. The preferred processalso yields other valuable products, such as sterols, from subsequentpurification steps.

The following non-limiting examples illustrate additional embodiments ofbiodiesel (methylic or ethylic esters) production and separation fromrefining soapstock. The disclosure below is of specific examples settingforth preferred methods. These examples are not intended to limit thescope, but rather exemplify preferred embodiments.

EXAMPLE 1

About 1 kg of refinery soapstock, with 65% moisture content, obtainedfrom refining soy oil, was dissolved in about 5 kg of ethyl alcohol andsaponified under reflux, in the presence of about 40 g of sodiumhydroxide solution/50% of concentration. The product was then heated atatmospheric pressure until the alcohol began to boil and reflux back tothe reacting medium, at a temperature around 65° C. to 90° C. Thereaction was performed for about 30 to 90 minutes, when substantialoil/triglycerides present in the refining soapstock were converted intosodium soap. The alcoholic solution was then filtered to separate theorganic material, mainly composed of lecithin and gums that, under theconditions above, do not react and are not soluble; about 107.8 g oflecithin and gums were obtained. This organic contaminant is present asa crystalline material.

The filtered lecithin and gums were then dried.

The alcoholic solution was again heated under the same reflux conditionsfor another period of about 30 to 90 minutes, after the addition ofabout 240 g of concentrated sulfuric acid. During this period, thesulfuric acid reacted with the sodium soap to form fatty acids andsodium sulfate. Under the reacting conditions, sodium sulfate, which isnot soluble, was filtered, producing 123 g of a white crystallinematerial.

After filtering sodium sulfate, the material was again heated underreflux to esterify the free fatty acids with the ethyl alcohol present.The reaction was performed for about 30 to 90 minutes. Excess sulfuricacid was neutralized by adding about 90 g calcium hydroxide. After theneutralization reaction of the free mineral acid, the material wasfiltered to remove the calcium salts formed. About 255.6 g calciumsulfate was produced.

The alcoholic solution obtained comprises a solution of ethyl esters ofsoy fatty acids in ethyl alcohol. The alcoholic solution was then heatedto distill excess ethyl alcohol. The distillation was performed attemperatures around 75° C. to 90° C. and at pressures around 760 mmHg to100 mmHg to yield ethyl alcohol and the ethyl ester/biodiesel.

The ethyl ester was centrifuged to remove the insoluble contaminants andother precipitates; about 239.2 g of impurities were eliminated.

The clear ethyl ester obtained from the soy oil refinery soapstock wasthen distilled for final purification and to meet the internationalBiodiesel specifications. This distillation was performed in adistillation system under vacuum, at a temperature around 180° C. to250° C. and a pressure varying from 3 mmHg to 760 mmHg. An ethyl esterfrom soy fatty acids was obtained; the analytical data of this productare found in Table 1 and the material meets the biodiesel specificationestablished worldwide. 326 g of ethyl esters/Biodiesel were obtained.

EXAMPLE 2

About 1 kg of refinery soapstock, with 65% moisture content, obtainedfrom refining of soy oil, was diluted in about 5 kg of methyl alcoholand saponified under reflux, in the presence of about 40 g of sodiumhydroxide solution/50% concentration. The product was then heated atatmospheric pressure until the point where the alcohol began to boil andreflux back to the reacting medium, at a temperature around 65° C. to90° C. The reaction was performed for about 30 to 90 minutes, whensubstantial triglycerides present in the refining soapstock wereconverted into sodium soap. The alcoholic solution was then filtered toseparate the organic material, mainly composed of lecithin and gumsthat, under the conditions above, did not react and are not soluble;about 109 g of lecithin and gums were obtained. This organic contaminantis present, after filtration, as a crystalline material.

The filtered lecithin and gums were then dried.

The alcoholic solution was heated under the same reflux conditions foranother period of about 30 to 90 minutes, after the addition of 235 g ofconcentrated sulfuric acid. During this period, the sulfuric acidreacted with the sodium soap to form fatty acids and sodium sulfate.Under the reacting conditions, sodium sulfate, which is not soluble, wasfiltered, producing 120 g of a white crystalline material.

After filtering sodium sulfate, the material was again heated underreflux to esterify the free fatty acids with the ethyl alcohol present.The reaction was performed for about 30 to 90 minutes. Excess sulfuricacid was neutralized by adding about 90 g calcium hydroxide. After theneutralization reaction of the free mineral acid, the material wasfiltered to remove the calcium salts formed. About 250 g calcium sulfatewas produced.

The alcoholic solution obtained comprises a solution of methyl esters ofsoy fatty acids in methyl alcohol. The alcoholic solution was thenheated to distill excess methyl alcohol. The distillation was performedat temperatures around 75° C. to 90° C. and at pressures around 760 mmHgto 100 mmHg to yield methyl alcohol and the methyl ester/biodiesel.

The methyl ester was centrifuged to remove the insoluble contaminantsand other precipitates; about 230 g of impurities were eliminated.

The clear methyl ester obtained from the soy oil refinery soapstock wasthen distilled for final purification and to meet the internationalBiodiesel specifications. This distillation was performed in adistillation system under vacuum, at a temperature around 60° C. to 100°C. and a pressure varying from 3 mmHg to 760 mmHg. A methyl ester fromsoy fatty acids was obtained; the analytical data of this product arefound in Table 1 and the material meets the biodiesel specificationestablished worldwide. 327 g of methyl esters/Biodiesel were obtained.

EXAMPLE 3

About 1 kg of refinery soapstock, with 65% moisture content, obtainedfrom refining soy oil, was dissolved in about 5 kg of ethylic alcoholand saponified under reflux, in the presence of about 40 g of sodiumhydroxide solution/50% of concentration. The product was then heated atatmospheric pressure until the alcohol began to boil and reflux back tothe reacting medium, at a temperature around 65° C. to 90° C. Thereaction was performed for about 30 to 90 minutes, when substantialoil/triglycerides present in the refining soapstock were converted intosodium soap. The alcoholic solution was then filtered to separate theorganic material, mainly composed of lecithin and gums that, under theconditions above, do not react and are not soluble; about 109 g oflecithin and gums were obtained. This organic contaminant is present asa crystalline material.

The filtered lecithin and gums were then dried.

The alcoholic solution was again heated under the same reflux conditionsfor another period of about 30 to 90 minutes, after the addition ofabout 240 g of concentrated sulfuric acid. During this period, thesulfuric acid reacted with the sodium soap to form fatty acids andsodium sulfate. Under the reacting conditions, sodium sulfate, which isnot soluble, was filtered, producing 125 g of a white crystallinematerial.

After filtering sodium sulfate, the material was again heated underreflux to esterify the free fatty acids with the ethyl alcohol present.The reaction was performed for about 30 to 90 minutes. Excess sulfuricacid was neutralized by adding about 90 g calcium hydroxide. After theneutralization reaction of the free mineral acid, the material wasfiltered to remove the calcium salts formed. About 250 g calcium sulfatewas produced.

The alcoholic solution obtained comprises a solution of ethyl esters ofsoy fatty acids in ethyl alcohol. The alcoholic solution was then heatedto distill excess ethyl alcohol. The distillation was performed attemperatures around 75° C. to 90° C. and at pressures around 760 mmHg to100 mmHg to yield ethyl alcohol and the ethyl ester/biodiesel.

The ethyl ester was centrifuged to remove the insoluble contaminants andother precipitates; about 240 g of impurities were eliminated.

The clear ethyl ester obtained from the soy oil refinery soapstock wasthen distilled for final purification and to meet the internationalBiodiesel specifications. This distillation was performed in adistillation system under vacuum, at a temperature around 180° C. to250° C. and a pressure varying from 3 mmHg to 760 mmHg. An ethyl esterfrom soy fatty acids was obtained; the analytical data of this productare found in Table 1 and the material meets the biodiesel specificationestablished worldwide. 352 g of ethyl esters/Biodiesel were obtained.

Below, Table 1, that presents the parameter and conditions in which theexamples described in this descriptive report were performed. TABLE 1Parameters Methodology Results Flash point in ASTM D 93 166° C. closedvessel Water and ASTM D 1796 0.0% in volume sediments Cinematic ASTM D445 4.52 cSt viscosity at 40° C. Sulfated ashes ASTM D 874 0.001% inweight Corrosion to ASTM D 130 1a copper at 50° C. Cetane index ASTM D4737 63.3 Ramsbotton ASTM D 524 2.06% in weight carbon residue Sodiumplasma spectrometry 7.00 mg/kg Potassium plasma spectrometry <2.0 mg/kgCalcium plasma spectrometry   10 mg/kg Magnesium plasma spectrometry 0.5 mg/kg Density 20/4° C. ASTM D 1298 876.1 kg/m³ Distillation underASTM D 1160 start - 318.0° C. vacuum 5% of the volume - 342.0° C. 10% involume - 343.0° C.  20% in volume - 344.0° C. 30% in volume - 346.0° C.40% in volume - 346.0° C. 50% in volume - 348.0° C. 60% in volume -349.0° C. 70% in volume - 351.0° C. 80% in volume - 353.0° C. 90% involume - 354.0° C. 95% in volume - 365.5° C. finish - 377.0° C.

Many modifications and variations of the embodiments described hereinmay be made without departing from the scope, as is apparent to thoseskilled in the art. The specific embodiments described herein areoffered by way of example only.

1. A process for producing biodiesel comprising: saponifying a soapstockwith an alkaline base in an alcohol to yield a saponified soapstock;filtering the solution of saponified soapstock to remove substantiallyinsoluble organic material; adding a mineral acid to the filteredsolution of saponified soapstock to form fatty acids and a mineral salt;and esterifying the fatty acids, thereby forming biodiesel.
 2. Theprocess of claim 1, further comprising neutralizing excess mineral acidafter addition of the mineral acid to the filtered solution.
 3. Theprocess of claim 2, further comprising removing salts formed from theneutralization.
 4. The process of claim 1, further comprising removingthe alcohol after esterification.
 5. The process of claim 4, wherein theremoval of alcohol is performed by distillation.
 6. The process of claim1, further comprising removing insoluble impurities afteresterification.
 7. The process of claim 6, wherein the removal ofinsoluble impurities is performed by centrifugation or filtration. 8.The process of claim 1, further comprising distilling the esters offatty acids after esterification.
 9. The process of claim 1, wherein thesoapstock originated from refining of an oil selected from the groupconsisting of soy oil, rice oil, sunflower oil, coconut oil, castor oil,chicken oil, cottonseed oil, corn oil, peanut oil, palm oil, and babassuoil.
 10. The process of claim 1, wherein the alcohol is methyl alcoholor ethyl alcohol.
 11. The process of claim 1, wherein the alkaline baseis sodium hydroxide or potassium hydroxide.
 12. Biodiesel obtained froma process comprising: saponifying a soapstock with an alkaline base inan alcohol to yield a saponified soapstock; filtering the solution ofsaponified soapstock to remove substantially insoluble organic material;adding a mineral acid to the filtered solution of saponified soapstockto form fatty acids and a mineral salt; and esterifying the fatty acids.13. Sterols obtained from a process comprising: saponifying a soapstockwith an alkaline base in an alcohol to yield a saponified soapstock;filtering the solution of saponified soapstock to remove substantiallyinsoluble organic material; adding a mineral acid to the filteredsolution of saponified soapstock to form fatty acids and a mineral salt;esterifying the fatty acids; removing insoluble impurities after theesterification; and distilling the solution of esters of fatty acidsafter esterification to obtain sterols.
 14. The sterols of claim 13,wherein the distillation step is performed by thin film evaporation orfalling film evaporation.
 15. The sterols of claim 14, wherein theprocess further comprises short-path distilling the product ofdistillation of the solution of esters of fatty acids.
 16. The sterolsof claim 15, wherein the process further comprises crystallizing theproduct obtained by short-path distillation.
 17. Organic materialobtained from a process comprising: saponifying a soapstock with analkaline base in an alcohol to yield a saponified soapstock; andfiltering the solution of saponified soapstock to obtain substantiallyinsoluble organic material.
 18. Mineral salts obtain from a processcomprising: saponifying a soapstock with an alkaline base in an alcoholto yield a saponified soapstock; filtering the solution of saponifiedsoapstock to remove substantially insoluble organic material; adding amineral acid to the filtered solution of saponified soapstock to formfatty acids and a mineral salt; and separating the mineral salt from thesolution.